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  <title>Execute command via shell and return the complete output as a string</title>

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</div><hr /><div id="function.shell-exec" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">shell_exec</h1>
  <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">shell_exec</span> &mdash; <span class="dc-title">Execute command via shell and return the complete output as a string</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-function.shell-exec-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="type">string</span> <span class="methodname"><strong>shell_exec</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$cmd</code></span>
   )</div>

  <p class="para rdfs-comment">
   This function is identical to the <a href="language.operators.execution.html" class="link">backtick operator</a>.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.shell-exec-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">cmd</code></em></dt>

     <dd>

      <p class="para">
       The command that will be executed.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.shell-exec-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   The output from the executed command or <strong><code>NULL</code></strong> if an error occurred or the
   command produces no output.
  </p>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    This function can return <strong><code>NULL</code></strong> both when an error occurs or the program
    produces no output. It is not possible to detect execution failures using
    this function. <span class="function"><a href="function.exec.html" class="function">exec()</a></span> should be used when access to the
    program exit code is required.
   </p>
  </p></blockquote>
 </div>


 <div class="refsect1 examples" id="refsect1-function.shell-exec-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-3585">
    <p><strong>Example #1 A <span class="function"><strong>shell_exec()</strong></span> example</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$output&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">shell_exec</span><span style="color: #007700">(</span><span style="color: #DD0000">'ls&nbsp;-lart'</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #DD0000">"&lt;pre&gt;</span><span style="color: #0000BB">$output</span><span style="color: #DD0000">&lt;/pre&gt;"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
 </div>


 <div class="refsect1 notes" id="refsect1-function.shell-exec-notes">
  <h3 class="title">注释</h3>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    当 PHP 运行在 <a href="features.safe-mode.html" class="link">安全模式</a> 时，不能使用此函数。
   </p>
  </p></blockquote>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.shell-exec-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.exec.html" class="function" rel="rdfs-seeAlso">exec()</a> - Execute an external program</span></li>
    <li class="member"><span class="function"><a href="function.escapeshellcmd.html" class="function" rel="rdfs-seeAlso">escapeshellcmd()</a> - Escape shell metacharacters</span></li>
   </ul>
  </p>
 </div>

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